Pheromones: they’re those chemical signals often associated with attraction. But there are many chemical signals we give off—including ones that might signal alarm, aggression or other emotions.

For example, take fear. If sweat contains compounds associated with fear, could someone smelling the sweat of a frightened person themselves wind up experiencing fear?

To find out, researchers had male subjects watch two movies. One was scary, and the other made viewers feel disgusted. The researchers then collected the participants’ sweat. Female subjects then smelled the sweat, while the scientists recorded their facial expressions. And the women who smelled “fear sweat” actually produced fearful facial expressions. While those who smelled the “disgust sweat” made disgusted faces. The inference is that the chemical compounds impelled the female subjects to remotely experience the same emotions felt by the sweaty males. The study is in the journal Psychological Science. [Jasper H. B. de Groot et al, Chemosignals Communicate Human Emotions]

So despite our lack of conscious awareness of interpersonal chemical communication, it seems that we nevertheless do physically and psychologically process such chemical signals. The researchers note that this study provides evidence that communication is not limited to language and visual cues: even we rational humans can become “emotionally synchronized” via scent.